Multimetal Adsorption Isotherm Studies of Ground Granulated Blast Furnace Slag from Municipal Solid Waste Leachate

Abstract

This paper aims to study the simultaneous adsorption of multiple heavy metal ions present in municipal solid waste (MSW) leachate. Leachate samples have been found to contain the heavy metal ions copper [Cu (1.22 mg/L)], zinc [Zn (2.86 mg/L)], lead [Pb (2.62 mg/L)], chromium [Cr (1.5 mg/L)], and nickel [Ni (0.65 mg/L)]. Ground granulated blast furnace slag (GGBS) will be used in this paper as adsorbent. The adsorptive capability of GGBS will be studied using the extended Langmuir isotherm model, Langmuir–Freundlich isotherm model, and multicomponent isotherm model. The extended Langmuir adsorption isotherm model fits the experimental values better than the other two models. The synergism, antagonism, and noninteraction effects will be studied based on the equilibrium metal uptake values. For all heavy metals present in the leachate used in this paper, the values of qmix/qo were >0, which indicated that multimetal adsorption was feasible by GGBS. This is the indication of enormous active sites on its surface. In addition, this was confirmed by the values of qmix/qo, because synergism was followed by antagonism. Ni ions showed a higher synergism effect that increased with an increase in GGBS dose. The adsorption effect of Cr experienced a transition from antagonism to synergism effect above 0.4 g of GGBS dose, which indicated the competition between Ni and Cr. The interactive effect for Pb fluctuated. Cu and Zn showed a strong antagonistic effect, Pb showed a moderate synergic effect, and Cr and Ni showed a strong synergic effect. The dose of GGBS has a predominant role in the adsorption of multiple heavy metal ions.